Lifting system, method for electrical testing, vibration damper, and machine assembly

ABSTRACT

The invention relates to a lifting system, comprising a piezoelectric actuator, a support, and a hydraulic stroke multiplier having an input and an output side, wherein with the input side of the hydraulic stroke multiplier said hydraulic stroke multiplier is tied to the piezoelectric actuator, and with the output side of the hydraulic stroke multiplier said hydraulic stroke multiplier is tied to the support. In the method for electrically testing an electronic component, the component is placed on the support of such a lifting system, and is lifted for positioning relative to a test contact. The vibration damper comprises such a lifting system. The machine assembly has a machine and such a vibration damper.

The invention relates to a lifting system, to a method for electrical testing, to a vibration damper and to a machine assembly.

A first aspect of the present invention relates to a lifting system and to a method for electrical testing: for the electrical testing of electronic components, in particular for the testing of LEDs, lifting systems are commonly required which lift the electronic component on a support. During the lifting of the electronic component, a contact is placed against it, such that the electronic component can have a measurement voltage applied to it for the electrical testing.

For the lifting systems required for this purpose, actuator concepts are required which exhibit both high dynamics and high positioning accuracy. Piezo actuators typically combine both of these characteristics. Piezo actuators however disadvantageously have only a stroke range of approximately 1.5% in relation to their length in the stroke direction; this means that, for customary piezo actuators, the stroke range amounts to only approximately 40 to 50 μm.

Against this background of the prior art, it is therefore firstly an object of the invention to provide an improved lifting system by means of which electrical testing of electronic components can be performed in a suitable manner. It is furthermore also an object of the invention to specify an improved method for the electrical testing of an electronic component.

A further aspect of the present invention relates to a vibration damper and to a machine assembly: during the operation of machines, in particular large electric motors, vibrations often arise which are excited for example by imbalances or which are magnetically excited by a rotating magnetic flux between rotor and stator.

It is disadvantageously possible for such vibrations to be coupled into a foundation and, for example, to cause surrounding installations to vibrate. Furthermore, the vibrations can be transmitted via the rotor to a plant (for example compressor) which is to be driven. Aside from comfort problems (noise, human vibration), this often leads to damage as a result of fatigue failure.

It is known for vibrations during the operation of electric motors to be prevented by eliminating the asymmetries that cause them, for example by way of balancing or by way of good magnetic design of the electric motor. However, a high level of balancing quality and a high level of homogeneity of the magnet guidance can be implemented only to a limited extent in technical terms, or only at very great expense.

Furthermore, passive vibration reduction is known: it is possible for viscoelastic damper elements (“rubber dampers”) to be provided on the machine foot. It is however disadvantageously also possible for quasi-steady-state forces, such as act for example during the build-up of torques, to lead to deformations.

Furthermore, in particular in automotive engineering, it is known to use hydraulic dampers which impart a damping action by way of hydraulic throttles, that is to say passively. However, by way of a build-up of preload pressure, quasi-steady-state forces can be applied such that, for example in the case of vehicles, active stabilization measures are possible (Electronically controlled active suspension system (ECASS), for example Active Body Control at Mercedes Benz, Active Roll Stabilization at BMW). However, in the case of traditional systems which operate with hydraulic pumps, the response time is extremely long, and/or the limit frequency is low (a small number of Hz).

Furthermore, magnetorheological dampers are known. Normally, these however realize merely an adjustable damping characteristic, but no active introduction of preload forces.

Furthermore, in buildings, in particular high-rise buildings, or bridges, overhead power lines and internal combustion engines, vibration absorbers are used for the reduction of vibrations. Vibration absorbers are composed of an absorber mass which is connected by way of an absorber spring and a damper to the system to be damped. Vibration absorbers extract, at their natural frequency, the vibration energy of the structure to be damped. All vibration absorbers disadvantageously require an additional mass, and are therefore expensive and heavy.

It is therefore also an object of the invention to provide an improved vibration damper and an improved machine assembly.

Said objects are achieved by way of a lifting system having the features specified in claim 1, by way of a method for the electrical testing of an electronic component, having the features specified in claim 8, by way of a vibration damper having the features specified in claim 10, and by way of a machine assembly having the features specified in claim 15. Preferred refinements of the invention are specified in the associated subclaims, in the following description and in the drawing.

The lifting system according to the invention has at least one piezo actuator. Furthermore, the lifting system has a support and a hydraulic stroke multiplier with an input and an output side, wherein the hydraulic stroke multiplier is attached by way of its input side to the at least one piezo actuator and by way of its output side to the support. The lifting system according to the invention thus advantageously combines firstly the high dynamics and the high positioning accuracy of a piezo actuator and also secondly the possibility of realizing large lift strokes by way of hydraulic stroke multipliers. In this way, it is possible to realize considerably longer lift strokes compared to conventional piezo actuators. At the same time, the lifting system according to the invention exhibits a very high system stiffness, which is considerably higher than in the case of lifting systems in which the piezo actuator strokes are boosted by way of solid-state joints. The required lift travel of the lifting system according to the invention can consequently be attained particularly rapidly and reliably. It is thus possible for the lifting system according to the invention to be used to particularly advantageous effect in particular in the case of time-critical applications. Furthermore, it is scarcely possible for the lifting system according to the invention to be resonantly excited so as to mechanically vibrate with natural resonance. The lifting system according to the invention is substantially insusceptible to this also.

In the lifting system according to the invention, the piezo actuator is preferably a piezo actuator with one actuation direction. It is expediently the case that, in the lifting system according to the invention, the hydraulic stroke multiplier is attached by way of its input side in the actuation direction to the piezo actuator. The piezo actuator is preferably a multi-layer piezo actuator. Multi-layer piezo actuators can provide a high power density with relatively low supply voltages.

The support is advantageously formed with a plate which, in particular, extends with its areal extent transversely with respect to the actuation direction, wherein the lifting system according to the invention preferably forms a lifting table.

It is expediently the case in the lifting system according to the invention that the hydraulic stroke multiplier comprises, at the input side and at the output side, in each case at least one piston chamber with a piston guided therein. Here, the cross sections of the at least one input-side piston chamber/of the piston chambers and of the at least one output-side piston chamber/of the piston chambers preferably differ from one another. It is self-evident that a cross section of a piston chamber is to be understood to be a section of the piston chamber transversely, that is to say perpendicularly, with respect to a guidance direction of the piston respectively guided in the piston chamber.

In the lifting system according to the invention, it is alternatively and likewise preferable for the hydraulic stroke multiplier to comprise, at the input side and at the output side, in each case at least one corrugated bellows, wherein the cross sections of the at least one input-side and of the at least one output-side corrugated bellows preferably differ from one another. In the present case, a cross section of a corrugated bellows is to be understood in each case to be a section transversely, that is to say perpendicularly, with respect to a folding direction of the corrugated bellows, that is to say a direction along which the corrugated bellows is collapsible. In particular, the cross section runs parallel to a preferably provided fold or bend line or along a circumferentially running undulation peak of an alternatively and likewise preferably provided undulation profile of the corrugated bellows.

In the lifting system according to the invention, it is preferably the case that the hydraulic stroke multiplier has, at the input side, two or three or four or more elements from the group comprising a corrugated bellows and a piston chamber with piston guided therein, wherein the hydraulic stroke multiplier has, at the output side, fewer elements from the abovementioned group, preferably precisely one element. The input-side elements are expediently in each case hydraulically connected to the at least one output-side element.

In a preferred refinement of the lifting system according to the invention, the input-side piston chamber(s) are connected, in particular hydraulically, to the output-side piston chamber(s), or the one or more input-side corrugated bellows are connected, in particular hydraulically, to the one or more output-side corrugated bellows, preferably by way of in each case one hydraulic throttle. By way of the configuration of the hydraulic throttle, it is possible for the damping characteristic of the lifting system according to the invention to be easily adapted.

The at least one input-side piston chamber and the at least one output-side piston chamber, in interaction with the pistons respectively guided therein, or else the at least one input-side corrugated bellows and the at least one output-side corrugated bellows, expediently each form fluid volumes, wherein the fluid volumes are coupled, preferably connected, to one another. The fluid volumes are suitably filled with incompressible fluid, in particular with a hydraulic fluid.

In the abovementioned refinements of the invention, the hydraulic multiplier action of the hydraulic stroke multiplier is realized by way of the input-side and output-side piston chambers and/or by way of the input-side and output-side corrugated bellows, which have different hydraulic cross sections and are fluidically connected to one another. Owing to the requirement for the hydraulic volume within the stroke multiplier of the lifting system according to the invention to remain constant, the stroke multiplier action of the hydraulic stroke multiplier is defined as the ratio of the input-side and of the output-side hydraulic cross section (for example the cross sections thereof transversely with respect to the respective guidance direction of the piston or transversely with respect to the fold direction). If multiple corrugated bellows and/or piston chambers are provided at the input side, it is naturally the case that the sum of the hydraulic cross sections thereof replaces the abovementioned input-side hydraulic cross section. Analogously, in the case of multiple output-side corrugated bellows and/or piston chambers being provided, the output-side hydraulic cross section is to be understood to mean the sum of hydraulic cross sections thereof. In this way, it is possible for changes in volume of the input-side piston chamber arising as a result of the input-side piston movement, or changes in volume of the input-side corrugated bellows arising as a result of input-side folding of the corrugated bellows, to cause, via the hydraulic connection, corresponding changes in volume of the output-side piston chamber or of the output-side corrugated bellows. Consequently, the result is particularly precise coupling of the input and output sides of the hydraulic stroke multiplier of the lifting system according to the invention.

In those refinements of the lifting system according to the invention in which the respective fluid volumes are realized way of input-side and output-side corrugated bellows, the respective fluid volumes are moreover sealed off by metallic means. Sealing problems of such fluid volumes are therefore prevented from the outset. A stroke multiplier action is, in these refinements, realized by way of flexible undulations in the bellows and the associated low axial stiffness. Here, the fluid volume is preferably as small as possible, such that the stiffness of the lifting system according to the invention is maximized. The fluid volumes are advantageously closed off, and consequently not subject to contamination. The lifting system according to the invention can consequently be of particularly durable and low-maintenance design.

Displacement bodies, composed in particular of metal, are in each case suitably provided in the hydraulic volumes of piston chambers or corrugated bellows. In this case, the overall stiffness of the lifting system according to the invention is greatly increased.

In the lifting system according to the invention, the cross section of the piston chamber at the input side is expediently larger than the cross section of the piston chamber at the output side, or the cross section of the corrugated bellows at the input side is larger than the cross section of the corrugated bellows at the output side. In this refinement, conversion of actuation strokes of the piezo actuator into relatively larger actuation strokes of the lifting system according to the invention is ensured.

In the method according to the invention for the electrical testing of an electronic component, the component is placed onto the support of a lifting system according to the invention as described above, and is suitably raised or lowered for the purposes of positioning relative to a test contact. By way of the lifting system according to the invention as described above, a very high system stiffness is realized, and at the same time, a required stroke is effected very rapidly. By means of the method according to the invention, it is consequently possible for a test time of an electronic component to be considerably shortened, because both the time and the reliability of the lift travel required for the test are improved. Furthermore, by way of the hydraulics, the lifting system according to the invention is intensely damped, and a “soft” lift curve is obtained, with which the electronic component can be raised or lowered particularly gently. By way of the method according to the invention, positioning of an electronic component relative to a test contact is consequently possible in a manner particularly well adapted to requirements. Ideally, the method according to the invention is carried out for the testing of an electronic component in the form of a light-emitting diode (LED).

The vibration damper according to the invention has a lifting system according to the invention as described above.

By contrast to traditional vibration absorbers (with auxiliary masses), the vibration damper according to the invention permits installation directly between a foundation and, for example, a foot of a machine to be damped. This is a particularly simple, efficient and robust approach both in terms of construction and in terms of control/regulation technology.

In the past, the use of piezo actuators for vibration reduction has often failed owing to the small deflections of piezo actuators. By way of the micro-hydraulic principle proposed here, using stroke multipliers according to the invention and the coupling of an arbitrary number of piezo actuators to an output-side corrugated bellows or an output-side piston chamber with piston guided therein, this limitation is effectively eliminated: according to the invention, it is possible to realize virtually any desired deflection of the lifting system according to the invention and of the vibration damper according to the invention at virtually any desired force level.

In the vibration damper according to the invention, the support is preferably designed for positively locking and/or cohesive and/or non-positively locking connection to a part of a machine, in particular to a machine foot.

In an advantageous refinement, the vibration damper according to the invention has an attachment piece and has a second hydraulic stroke multiplier with an input and an output side, which second hydraulic stroke multiplier is attached by way of its input side to a further linear actuator and by way of its output side to the attachment piece.

In this way, not only is it possible for vertical vibrations to be dampened, such as is the case by way of the vibration damper according to the invention with the lifting system according to the invention, but it is additionally possible for vibrations in further degrees of freedom, for example vibrations in horizontal spatial directions, to be dampened by way of the second hydraulic stroke multiplier with the further linear actuator.

The vibration damper according to the invention expediently comprises a control unit which is designed to control the piezo actuator in a first operating mode such that the total force acting on the lifting system remains constant, and/or to control the piezo actuator in a second operating mode such that the support vibrates with the least possible deflection.

In the case of the vibration damper according to the invention, it is preferably provided that, instead of the at least one piezo actuator, at least one other actuator is provided, in particular at least one magnetic and/or magnetostrictive and/or electrostrictive actuator and/or an actuator which is based on the shape memory principle, preferably on the principle of magnetic shape memory.

The machine assembly according to the invention has a machine, in particular an electric motor, and has at least one vibration damper as described above, which at least one vibration damper is attached, preferably by way of an attachment part, to the machine, preferably to at least one foot of the machine.

The machine assembly according to the invention can be of lightweight and compact form, for example by virtue of a typical machine foot being equipped with a vibration damper, which necessitates only minor changes or no changes in space requirement or weight. It is thus possible for machine assemblies according to the invention to be formed with minor changes in relation to non-vibration-damped machines. In particular, it is not necessary to provide space for large absorber masses. This can considerably improve customer acceptance. The reduction of vibrations of the machine is in this case possible in different variants. The decoupling of the machine of the machine assembly according to the invention and a foundation on which the machine is positioned prevents oscillating forces from being introduced into the foundation. The calming has the effect that forces are introduced into the machine such that the latter (or one or more of its parts) is prevented from vibrating. In mixed forms, a combination of the above features is provided, such that the vibration of the machine or of parts of the machine is reduced, but at the same time an introduction of force into the foundation is kept within an acceptable range.

In particular, according to the invention, in each case one vibration damper is provided between a foot of the machine and a foundation on which the machine is positioned. In the case of a machine, for example in the form of a typical electric motor, with four feet, it is thus expediently the case that four vibration dampers according to the invention are used; this is correspondingly a distributed vibration damping system.

In the case of the vibration damper according to the invention, and in the case of the machine assembly according to the invention, it is preferably the case that the lifting system according to the invention can be deflected with frequencies from steady-state operation (0 Hz) up to a maximum frequency, preferably at least 5000 cycles/min, in particular at least 10,000 cycles/min. The lifting system can be suitably deflected within the stated frequency range with a deflection of up to 200 micrometers, in particular with a deflection of up to 800 micrometers.

In general, the maximum frequency is determined by the maximum operating frequency of the machine (expediently at least 5000 cycles/min) multiplied by the number of pole pairs (expediently at least 2), for example of an (electric) motor of the machine. The required maximum deflection is determined from the dynamic system configuration and is dependent primarily on the type of foundation, in particular on the (absence of) stiffness of the foundation.

The required maximum deflection typically lies in the range from 200 micrometers to 800 micrometers. By way of deflection of the lifting system according to the invention of the vibration damper according to the invention, a controllable or regulable deflection or force is set between the foundation and machine. In this way, in particular, the possibilities described in more detail below for vibration reduction of the machine assembly are made available, which are expediently realized in the control device described above:

1. Decoupling:

The vibration of the machine is decoupled from the foundation, that is to say the foundation is subjected only to quasi-steady-state forces (weight of the machine and/or quasi-steady-state torque loading). For this purpose, the deflection of the piezo actuator is expediently controlled and/or regulated such that the force on the piezo actuator and/or on the output side of the hydraulic stroke multiplier is as constant as possible.

For this purpose, it is advantageously the case that force sensors are integrated into the piezo actuator and/or the hydraulic stroke multiplier. The machine can thus, in effect, vibrate freely.

The motor vibration is thus not reduced in relation to the non-damped system. However, the vibrations coupled into the surroundings are suppressed or greatly reduced, which is advantageous with regard to noise or human vibration.

2. Calming:

The deflections of the piezo actuator are controlled such that the machine or parts of the machine, in particular a motor block or a motor shield or a motor bearing or a rotor or an axle of an electric motor, is or are prevented from vibrating, that is to say is or are in effect “constrained”. For this purpose, forces must be coupled in which are substantially opposed, but of equal magnitude, to the excitation forces. It is advantageously the case that, for this purpose, sensors are attached to the parts to be calmed, and the amplitude, frequency and phase angle are calculated by way of suitable algorithms (see below). The machine vibrations are greatly reduced in this way. However, at present, high forces are introduced into the foundation, which can in turn—depending on the type of construction—incite vibration of said foundation.

3. Mixed Forms:

By way of a suitable quality function, an advantageous combination of decoupling and calming is determined. For example, it may be an aim to keep a machine vibration amplitude below a certain threshold value, but to do so with the least possible introduction of force into a foundation of the machine. This may be realized in a manner dependent on the operating point (for example rotational frequency, applied torque), either by way of a suitable adaptive algorithm or pilot control.

In general, multiple piezo actuators with input-side corrugated bellows or piston chambers with pistons guided therein are attached. Here, all of the piezo actuators can preferably be controlled uniformly, such that altogether, with n piezo actuators, an n-fold deflection of the lifting system according to the invention with the same force can be achieved. This arrangement makes it possible to implement an identical-parts concept, that is to say for the same piezo actuators to be used, for a whole series of lifting systems according to the invention and vibration dampers according to the invention. Furthermore, the fail-safety of the lifting system according to the invention and of the vibration damper according to the invention is increased, because in the event of failure of a single piezo actuator, the entire lifting system or the entire vibration damper continues to operate, albeit with reduced performance.

For the control of multiple provided vibration dampers according to the invention of a machine assembly according to the invention, distributed control is generally necessary. Known algorithms, such as the skyhook algorithm or the filtered-x LMS algorithm, are expedient for this purpose.

As a simple alternative, it is expedient to create, from measurement values, a machine model which permits a prediction of the expected vibration behavior at a particular frequency. On this basis, it is possible to calculate amplitudes and phases of the individual vibration dampers, which then need merely be controlled with rotational angle synchronicity. The rotational angle of the motor can be gathered from the control (inverter) of the motor, such that in this way, simple and robust control of the vibration damper can be realized.

The invention will be discussed in more detail below on the basis of an exemplary embodiment illustrated in the drawing:

In the figures:

FIG. 1 shows a lifting system according to the invention which has a hydraulic stroke multiplier with hydraulically interconnected piston chambers, in a diagrammatic sketch in longitudinal section,

FIG. 2 shows a vibration damper according to the invention which is designed for the vibration damping of an electric motor, in a diagrammatic sketch in longitudinal section, and

FIG. 3 shows a conventional machine (a) and a machine assembly according to the invention (b) with a vibration damper according to the invention as per FIG. 2, in a diagrammatic sketch in longitudinal section.

The lifting system according to the invention illustrated in FIG. 1 has a piezo actuator 5 which is designed for effecting an actuation stroke in an actuation direction S. For this purpose, the piezo actuator 5 is fixedly clamped at one side R. From that side R, the piezo actuator 5 extends in the actuation direction S with an electrically manipulable length dimension in the longitudinal direction. The piezo actuator 5 therefore has, averted from its clamped side R, a free end M which is spaced apart to a variable extent in the longitudinal direction from the clamped side R. The free end M of the piezo actuator 5 is attached to an input side E of a hydraulic stroke multiplier 10.

The stroke multiplier 10 has an output side A which is attached to a support in the form of a lifting table panel 15. The lifting table panel 15 is merely indicated in FIG. 1 (as a dashed vertical line).

The hydraulic stroke multiplier 10 comprises an input-side piston chamber 20 and, hydraulically coupled thereto, an output-side piston chamber 25. A piston 30 is guided in the input-side piston chamber 20 so as to be actuable at an input side, that is to say a handle 32 leads out of the piston chamber 20 at the input side. A piston 35 is likewise guided in the output-side piston chamber 25. The piston 35 has a handle 37 which is led out of the piston chamber 25 at the output side. Both the piston 30 of the input-side piston chamber 20 and the piston 35 in the output-side piston chamber 25 are guided in the respective piston chamber 20, 25 so as to be movable in each case in and oppositely to the actuation direction S.

The input-side piston chamber 20 and the output-side piston chamber 25 are hydraulically connected, and thus coupled, to one another via a hydraulic throttle 40.

The lifting system according to the invention illustrated in FIG. 1 is operated as follows:

In a manner known per se, a voltage is applied to the piezo actuator 5 such that the free end M of the piezo actuator 5 deflects in the actuation direction S. The free end M of the piezo actuator 5 is rigidly coupled in terms of motion to the handle 32 of the piston 30 which is guided in the input-side piston chamber 20. As a result, during the deflection of the free end M of the piezo actuator 5, the piston 30 is moved in the actuation direction S within the input-side piston chamber 20.

A hydraulic oil is situated in the input-side piston chamber 20 at that side of the piston 30 which is averted from the piezo actuator 5. Consequently, in the input-side piston chamber 20, the piston 30 delimits the volume occupied by the hydraulic oil in the input-side piston chamber 20. During the movement of the piston 30 in the input-side piston chamber 20 in the actuation direction S, the volume available for the hydraulic oil within the input-side piston chamber 20 consequently decreases. As a result, hydraulic oil is displaced out of the input-side piston chamber 20 and passes via the hydraulic throttle 40 into the output-side piston chamber 25 of the hydraulic stroke multiplier 10. In the output-side piston chamber 25, too, the volume available for the hydraulic oil is delimited by a piston, in this case the piston 35 that is guided in the output-side piston chamber 25. Owing to the hydraulic oil which additionally flows into the output-side piston chamber 25 which is likewise filled with hydraulic oil, it is consequently the case that the piston 35 that is guided in the output-side piston chamber 25 is moved in the actuation direction S.

The lifting table plate 15 is rigidly coupled in terms of motion, specifically directly fastened in the exemplary embodiment shown, to the handle 37 of the piston 35 that is guided in the output-side piston chamber 25, which piston is moved in the actuation direction S. Consequently, the lifting table panel 15 moves in the actuation direction S.

Owing to the considerably larger cross section, perpendicular to the actuation direction S, of the input-side piston chamber in relation to the output-side piston chamber 25, the lifting table panel 15 does not move by the same actuation stroke as that by which the free end M of the piezo actuator 5 moves in the actuation direction S (approximately 50 μm in the exemplary embodiment illustrated). Rather, the hydraulic stroke multiplier 10 has a considerably greater transmission ratio. As a result, the lifting table panel 15 moves in the actuation direction S by a stroke which is defined by the actuation travel of the free end M of the piezo actuator 5 multiplied by a transmission ratio factor >1, in the illustrated exemplary embodiment a factor of 100 (the dimensions of the piston chambers 20, 25 shown in FIG. 1 are not illustrated to scale). In this way, through corresponding control of the piezo actuator 5, it is possible to realize a corresponding actuation stroke of the lifting table panel 15, of 5 millimeters in the exemplary embodiment shown.

By contrast, if the free end M of the piezo actuator 5 is moved counter to the actuation direction S, the lifting table panel 15 also moves counter to the actuation direction S by said actuation travel scaled by the transmission ratio factor of 100.

In the method according to the invention for the electrical testing of a light-emitting diode, the lifting system illustrated in FIG. 1 is positioned such that the actuation direction S is oriented parallel or non-parallel with respect to the direction along which the gravitational force acts. That is to say the lifting system illustrated in FIG. 1 is oriented with its actuation direction S vertically, for example such that the lifting table panel 15 is situated above the piezo actuator 5.

For the testing of the light-emitting diode, the light-emitting diode is placed onto the lifting table panel 15. For the electrical testing of the light-emitting diode, a test contact (not explicitly shown in FIG. 1) is used which is arranged rigidly relative to the clamped end R of the piezo actuator 5. The light-emitting diode (not explicitly shown in FIG. 1) is suitably raised or lowered by way of the lifting table panel 15 for the purposes of positioning relative to said test contact. In this way, the light-emitting diode is brought into contact with the test contact and, in the process, has a test voltage applied to it. Electrical testing of the light-emitting diode can subsequently be performed.

It is self-evident that, instead of the input-side piston chamber 20 with the piston 30 guided therein and the output-side piston chamber 25 with the piston 35 guided therein, it is also possible for an input-side corrugated bellows and an output-side corrugated bellows to be provided, which, similarly to the arrangement illustrated in FIG. 1, are hydraulically coupled to one another via a hydraulic throttle 40. Instead of the coupling of the free end M of the piezo actuator 5 to the handle 32 of the piston 30 that is guided in the input-side piston chamber 20, the free end of the piezo actuator 5 is instead coupled to that end of the input-side corrugated bellows which faces toward the free end of the piezo actuator 5. Here, the input-side corrugated bellows has a fold direction which runs along the actuation direction S as per FIG. 1. Correspondingly, an end, facing toward the lifting table panel 15, of the output-side corrugated bellows is attached to said lifting table panel. The fold direction of the output-side corrugated bellows in this case runs oppositely to the actuation direction S as per FIG. 1. It is also self-evident that, in the method according to the invention discussed above, it is also possible for electronic components other than a light-emitting diode to be electrically tested.

The vibration damper 200 according to the invention illustrated in FIG. 2 serves for the damping of vibrations of a machine, specifically of an electric motor 300 in the illustration of FIG. 3.

The vibration damper 200 comprises four piezo actuators 5, which are each fixedly clamped at one side R (in the illustration as per FIG. 2, only two of these piezo actuators 5 are shown). From that side R, the piezo actuator 5 extends in each case in the actuation direction S with an electrically manipulable length dimension in the longitudinal direction. The piezo actuator 5 thus has in each case a free end M averted from its clamped side R, which free end is variably spaced apart from the clamped side R in the longitudinal direction. The respective free end M of the respective piezo actuator 5 is attached to an input side E of a hydraulic stroke multiplier 10′. The four piezo actuators 5 are deflected synchronously by way of a control device (see below).

By contrast to the exemplary embodiment illustrated in FIG. 1, the hydraulic stroke multiplier 10′ illustrated in FIG. 2 firstly comprises an input-side corrugated bellows 220 instead of an input-side piston chamber 20 with piston 30 guided therein, and comprises an output-side corrugated bellows 225 instead of an output-side piston chamber 25 with piston 35 guided therein, which output-side corrugated bellows is hydraulically coupled to the input-side corrugated bellows 220, similarly to the arrangement illustrated in FIG. 1, via a hydraulic throttle 40.

In a further difference in relation to the hydraulic stroke multiplier 10 illustrated in FIG. 1, it is the case in the hydraulic stroke multiplier 10′ illustrated in FIG. 2 that not only one but rather four input-side corrugated bellows 220 are in each case hydraulically connected to a single output-side corrugated bellows 225: the output-side corrugated bellows 225 is, for this purpose, movable in a vertical direction, that is to say the output-side corrugated bellows 225 is collapsible in a vertical direction. The vertically upwardly extending side of the output-side corrugated bellows 225 terminates, at a face side, with a machine support 230. The machine support 230 serves as a support surface for a motor foot F of the electric motor 300 (see in particular FIG. 3). Furthermore, the machine support 230 has a thread (not separately illustrated) which corresponds with a thread of the motor foot F. By way of said thread, the motor foot F can be fixed to the machine support 230.

The input-side corrugated bellows 220 are, by contrast to the output-side corrugated bellows 225, movable horizontally, that is to say the input-side corrugated bellows 220 are collapsible in a horizontal direction. In a vertical view onto the horizontal plane, the four input-side corrugated bellows 220 extend with their horizontal directions, in which they are in each case movable/collapsible, in stellate fashion radially away from the output-side corrugated bellows 225.

The output-side corrugated bellows 220 are supported relative to a foundation B.

The machine assembly according to the invention illustrated in FIG. 3b (by contrast to a conventional machine a)) comprises the electric motor 300 with four motor feet F and the four vibration dampers 200, to which each of the four motor feet of the electric motor 300 is connected.

The electric motor 300 comprises a stator and a rotor (not shown in detail) which rotates relative to the stator (not illustrated in detail) with a frequency up to a maximum operating frequency of 5000 revolutions per minute about an axis A. The electric motor 300 has 2 pole pairs (not explicitly shown), such that the maximum frequency of vibrations encountered maximally during operation is 10,000 cycles/minute. Furthermore, during the operation of the motor in the frequency range from 0 to 10,000 cycles/minute, maximum deflections of 800 micrometers occur.

For this purpose, the vibration damper 200 according to the invention has force sensors (not separately illustrated) which are each arranged at the input side on the output-side corrugated bellows 225 and detect forces acting there. By way of the force sensors, the respectively acting force is detected and transmitted to a control device (not separately shown). By way of the control device, the piezo actuators 5 are controlled in terms of their deflection with respect to time such that the respectively acting force is, as far as possible, eliminated.

Alternatively, in a further exemplary embodiment which is not separately illustrated, it is possible for acceleration sensors to be provided instead of the force sensors, which acceleration sensors are arranged in each case on the motor feet F or on the rotor of the electric motor 300 and which detect the vibrations of the electric motor 300 in terms of amplitude, frequency and phase. The sensors transmit the detected data to a control device, which controls the piezo actuator 5 such that the (spatial) amplitude of the motor vibrations is, as far as possible, eliminated.

In a further exemplary embodiment, mixed forms of the two abovementioned control configurations are also possible: accordingly, a suitable quality function may be provided, the implementation of which has the effect that, for example, an amplitude of the motor vibrations is kept below a particular threshold value, with this being realized with the least possible introduction of force into the foundation B.

In a further exemplary embodiment which is not separately illustrated and which otherwise corresponds to the illustrated exemplary embodiment, an attachment piece for attachment to the electric motor 30, and an additional, second hydraulic stroke multiplier, are additionally provided, said additional, second hydraulic stroke multiplier having an input side, which is attached to a further linear actuator, and an output side, which is attached to the attachment part.

In the abovementioned exemplary embodiments, the four vibration dampers 200 are controlled by way of distributed control: for example, in this case, use is made of the skyhook algorithm or the filtered-x LMS algorithm.

Alternatively, in a further exemplary embodiment, use is made of a machine model for the electric motor 300, which machine model permits a prediction of the expected vibration behavior at a particular frequency. On this basis, it is possible to calculate the amplitudes and phases of the individual vibration dampers to be set, which then need merely be controlled with rotational angle synchronicity with the operating frequency of the electric motor 300. The rotational angle of the electric motor 300 can be gathered from the control, for example an inverter (not shown), of the electric motor 300, such that in this way, simple and robust control of the piezo actuator 5 can be realized. 

1. A lifting system, having at least one piezo actuator (5), a support (15), and a hydraulic stroke multiplier (10) with an input and an output side, which hydraulic stroke multiplier is attached by way of its input side to the piezo actuator (5) and by way of its output side to the support (15).
 2. The lifting system as claimed in claim 1, in which the hydraulic stroke multiplier (10) comprises, at the input side and at the output side, in each case at least one piston chamber (20, 25) and a piston (30, 35) guided therein, wherein the cross sections of the input-side and of the output-side piston chamber(s) (30, 35) preferably differ from one another.
 3. The lifting system as claimed in one of the preceding claims, in which the hydraulic stroke multiplier (10) comprises, at the input side and at the output side, in each case at least one corrugated bellows, wherein the cross sections of the one or more input-side and output-side corrugated bellows differ from one another.
 4. The lifting system as claimed in one of the preceding claims, in which the hydraulic stroke multiplier has, at the input side, two or three or four or more elements from the group comprising a corrugated bellows and a piston chamber with piston guided therein, wherein the hydraulic stroke multiplier has, at the output side, fewer elements from the abovementioned group, preferably precisely one element.
 5. The lifting system as claimed in one of the preceding claims, in which input-side and output-side piston chamber(s) (20, 25) or one or more input-side and output-side corrugated bellows are hydraulically connected to one another.
 6. The lifting system as claimed in one of the preceding claims, in which one or more input-side and output-side corrugated bellows or input-side and output-side piston chamber(s) (20, 25) are connected to one another by way of one or more hydraulic throttle(s) (40).
 7. The lifting system as claimed in one of the preceding claims, in which the cross section of the input-side piston chamber (20) is greater than the cross section of the output-side piston chamber (25), or in which the cross section of the input-side corrugated bellows is greater than the cross section of the output-side corrugated bellows.
 8. A method for the electrical testing of an electronic component, in which method the component is placed onto the support (15) of a lifting system as claimed in one of the preceding claims, and is raised or lowered for the purposes of positioning relative to a test contact.
 9. The method for electrical testing as claimed in the preceding claim, which method is carried out for the testing of an electronic component in the form of a light-emitting diode (LED).
 10. A vibration damper which has a lifting system as claimed in one of claims 1 to
 7. 11. The vibration damper as claimed in the preceding claim, in which the support is designed for positively locking and/or cohesive and/or non-positively locking connection to a part of a machine, in particular to a machine foot.
 12. The vibration damper as claimed in one of the preceding claims, in particular as claimed in claim 10 or 11, which furthermore has a linear actuator, an attachment piece and a second hydraulic stroke multiplier (10) with an input and an output side, which second hydraulic stroke multiplier is attached by way of its input side to the linear actuator and by way of its output side to the attachment piece.
 13. The vibration damper as claimed in one of the preceding claims, comprising a control unit which is designed to control the piezo actuator in a first operating mode such that the total force acting on the lifting system remains constant, and/or to control the piezo actuator in a second operating mode such that the support vibrates with the least possible deflection.
 14. The vibration damper as claimed in one of the preceding claims, in which, instead of a piezo actuator, some other actuator is provided, in particular a magnetic and/or magnetostrictive and/or electrostrictive actuator and/or an actuator which is based on the shape memory principle, preferably on the principle of magnetic shape memory.
 15. A machine assembly having a machine, in particular an electric motor, and having at least one vibration damper as claimed in one of the preceding claims, which at least one vibration damper is attached, preferably by way of an attachment part, to the machine, preferably to at least one foot of the machine. 